Although Sixnet VT-Modems are relatively easy to use, there can be instances where more complex situations can arise when connecting them to other devices. The VT-Modem-3 must be configured with the Sixnet VT-Modem Wizard due to the RS422 and RS485 features. Please see the sections below:
- Introduction to the VT-Modem-3
- Troubleshooting and Frequently Asked Questions
- Using the VT-Modem Wizard to configure your Modem
- Technical Notes for connecting to various PLC’s and other equipment
Introduction to the VT-Modem-3
The following information is contained in the VT-Modem-1, 2 & 3 User Manual, in addition to the information found in this document. It can be downloaded from: here
The following sections are contained in the user manual:
|Section 2||Performance Specifications|
|Section 3||VT-Modem Mounting|
|Section 4||Electrical Connections|
|Section 5||Modem Configuration|
|Section 6||AT Command Summary|
|Section 7||S-Register Summary|
|Section 8||Maintenance Information|
|Section 9||Product Support & Other Documents|
Troubleshooting and Frequently Asked Questions
1. I can’t seem to detect the VT-Modem-3, why?
Answer: Verify the following:
a. Verify that you have selected the appropriate com port that is connected from your PC to the VT-Modem-3.
b. Verify that you are using a DB-9 Null-Modem cable.
c. Verify that you have applied 10-52 VDC to VT-Modem-3.
2. I ordered a VT-Modem-3, but it is being detected as a VT-Modem-1, why?
Answer: This is usually caused by the Modem Wizard Software detecting your PC’s internal modem. Follow the steps in 3a-e below to determine if this is the case.
3. I can’t write my configuration to the VT-Modem-3. I keep getting an error message that says problems encountered while sending string AT…..etc. See error example below:
Answer: This is usually caused from the VT-Modem Wizard Software detecting the internal modem of the PC and not the internal socket modem of the VT-Modem-3. Follow the steps below to determine which modem you are actually detecting:
a. Open up a terminal emulator program, such as, hyperterminal, teraterm, or the Run Terminal Emulator Icon in the VT-Modem Wizard Software.
b. Type the command ATI3 and hit the enter key on your keyboard. You should see one of the following; P2109-V90, V2.100-V34_2M-DLS, or CX81802-V34. If you see any other alphanumeric characters not described above, then you are detecting the internal modem of your PC and not the VT-Modem-3.
c. If you see nothing after typing the ATI3 command, then type the command ATE1 and hit the enter key on your keyboard and repeat the ATI3 command. If you still see nothing, you may still be detecting the internal modem on your PC.
d. If you do see the alphanumeric characters described above but still can’t write the configuration to the VT-Modem-3,report error message to support here: https://redlioncontrols.zendesk.com/hc/en-us/requests/new
e. To force the Modem Wizard Software to detect the VT-Modem-3 and not the internal PC Modem, see 4. below:
4. How do I get the VT-Modem Software to detect the VT-Modem-3 and not my PC’s internal modem?
Answer: Follow the steps below to disable you PC’s internal modem:
a. Click on Start, My computer, and then View System Information under the System Tasks. You should see the System Properties below:
b. Click on Hardware tab:
c. Click on Device Manager:
d. Click on the + sign, then right click on your PC’s internal modem and select Disable:
e. Select Yes and you should see a red x on your selection indicating that it is now disabled:
f. Restart your computer and you should now be able to detect the VT-Modem-3 using the Modem Wizard Software.
5. The VT-Modem-3 continuously rings but never answers the call, why?
Answer: The modem should answer the call on the number of rings specified in the S0 register, which is set in the VT-Modem-Wizard on the Modem Parameters Page, “Enable Auto-Answer On (x) Rings, where x = the number of rings set in the drop down box. You can also set this parameter by entering the command ATS0=X&W0&W1, where X = the number of rings, in the run terminal emulator of the modem wizard or any other terminal emulator program.
6. I can never get a carrier detect (CD) LED, unless I remove the devices that are connected to the serial port. How do I fix this?
Answer: Sometimes PLC’s or other serial devices send random characters that may interfere with the connection. To fix this, go to the RS485/RS232 Modem Parameters page of the wizard and click on the radio button for “Block Com Port till connected”, it should turn light blue. Make sure all parameters are set as desired and write the configuration to the modem.
7. If I cycle power or lose power to my local VT-Modem-3, I can’t seem to re-establish a connection to the remote Modem.
Answer: It is possible for the remote VT-Modem unit to get stuck in a carrier detect (CD) LED “On” state. If this is the case, you will have to cycle power to the unit. To prevent having to drive to the remote location, or having someone cycle power for you every time that this situation occurs, enter the following command in the user defined “AT” String on the modem parameters page of the wizard, or terminal emulator in the wizard, or through another terminal emulator program. ATS10=8S30=3
8. I was able to connect to the modem once, but I can’t dial-in to it again. I keep getting a busy signal when I attempt to dial-in.
Answer: There are some instances where the quality of the phone line is degraded, or there is enough noise on the line to make the VT-Modem-3 interpret this noise as a connection. This results in the last call never being dropped. If this is the case, it will be required to cycle power to the VT-Modem. To prevent having to drive to the remote location, or having someone cycle power for you every time that this situation occurs, enter the following command in the user defined “AT” String on the modem parameters page of the wizard, or terminal emulator in the wizard, or through another terminal emulator program. ATS10=8S30=3
9. Can the VT-Modem-3 communicate via RS232 and RS422/RS485 simultaneously?
Answer: No, only one mode of operation can communicate at a time.
10. Most other questions are addressed in the user manual (See Section 1 for the link). If you need more assistance, please contact the next level of support for resolution.
Using the VT-Modem Wizard to configure your modem
Download Instructions and Procedures
1. To download the latest version of the Sixnet VT-Modem Wizard, go to http://www.redlion.net/files/1319/7177
After downloading, follow the installation instructions to install the wizard.
2. Open the VT-Modem Wizard Utility
3. Click “Next” and you should see:
4. Connect a DB-9 cable from your PC to the VT-Modem-3, select the appropriate com port and apply power.
5. Click on the Red Bar at the top that says “NO MODEM DETECTED. PLEASE CLICK
HERE TO DETECT THE MODEM”. You should see:
6. Click on “Detect Modem” and a blue bar with VT-MODEM-3 (Modem with RS485 Port), Rev 3. Firmware V1.04 (Note – It may say Rev. 1, Rev. 2 or Rev. 3 depending on the internal socket modem) should appear. If it detects the modem as a VT-Modem-1, see Section 2 for troubleshooting.
7. Set the communication parameters for the serial device that you will be connecting to and click Next. You should see the RS485/RS232 Modem Parameters Page:
8. Select the desired Communication Mode in the drop down box and click next to see the Modem Parameters Page:
9. Select the appropriate Modem to Modem Parameters. We recommend the default settings except for an Auto detect Speed of 33600, unless specified differently in a .6ms configuration or by a 3rd party device specification.
10. Click Next, and click on Write Configuration to the Modem:
11. When the modem has been successfully loaded, you should see:
12. We recommend that you save your configuration file in case it becomes necessary to configure a similar project, or in the event that the modem has to be replaced.
It is the customer's responsibility to review the advice provided herein and its applicability to the system. Red Lion makes no representation about specific knowledge of the customer's system or the specific performance of the system. Red Lion is not responsible for any damage to equipment or connected systems. The use of this document is at your own risk. Red Lion standard product warranty applies.
Red Lion Technical Support
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